Most conventional automobiles include a power assist steering system. The power assist system can be electronically or hydraulically based. Existing systems include constant flow, variable flow, pressure control systems and electric motor-driven systems. It can be difficult to distinguish system failures (either in real time driving conditions or during stationary servicing). For example, a hydraulic power steering system may be malfunctioning due to a restriction in the fluid line, a sticking pump control valve within the system or an abnormality with the system pump. Current automotive hydraulic systems lack adequate means to detect and more importantly diagnose a system fault. Accordingly, it is difficult to identify the necessary repair.
In some automobiles the vehicle operator—through observation or indicators—is made aware that some repair is needed. The driver may notice functional degradations, excessive noise or a leakage of fluid. However, the vehicle and service centers lack a computer-based means for diagnosing the specific system failure. When this occurs permanent damage to the system may have occurred before proper diagnosis. The vehicle is taken in for repair and typically a service technician must rely on information gained from the driver by trial and error to determine the specific repair needed. Often when misdiagnosis occurs, properly functioning components are replaced and any number of return visits may be required. A better means of diagnosing system ailments is desired.
Some existing steering systems include an electronic motor that powers the hydraulic steering system. Such systems may include a processor that monitors the electric motor performance during operation. For example, U.S. Pat. No. 7,210,554 titled “Power Steering System” teaches an abnormal condition monitoring circuit that detects abnormalities in the pump motor. The abnormal condition monitoring circuit, however, is not compatible with engine driven steering systems that do not include an electric motor-driven pump. Accordingly, there exists a need for a more precise means of diagnosing system ailments in hydraulic power steering systems with or without electric pump motors.
Therefore, it is desirable to have a computer-implemented method of diagnosing a vehicle power steering system that can detect a specific steering system condition and send warning of the same. The system should be able to diagnose system ailments in hydraulic power steering systems with or without electric pump motors.